1. Field of the Disclosure
The present application relates to an organic light emitting diode display device.
2. Description of the Related Art
As the information society spreads, the requirements for display devices are varied and gradually increasing. In accordance therewith, a variety of flat panel display devices with features such as slimness, light weight, low power consumption and so on are being researched. The flat panel display devices include liquid crystal display (LCD) devices, plasma display panels (PDP), organic light emitting diode (OLED) display device and so on, have been researched.
The OLED display device corresponds to a self-luminous display device which emits red, green and blue lights using organic compounds formed on a transparent substrate. In general, the OLED display device includes an OLED panel and a driving circuit. As such, the OLED display device does not require a separated light source, unlike the LCD device. In accordance therewith, the OLED display device can provide a simpler fabrication procedure and a lower fabrication cost, compared to the LCD device. In view of this point, the OLED display device is being spotlighted as a next generation flat panel display device. Also, the OLED display device provides a wider viewing angle and a higher contrast ratio, compared to the LCD device. Moreover, the OLED display device can be driven by a low direct-current voltage and endure well an external impact. Furthermore, the OLED display device has a short response time and a wide workable temperature range.
More specifically, the OLED display device of an active matrix type allows a voltage, which is applied to a pixel region and is used to control a current, to be charged into a storage capacitor and maintained until a next frame signal is applied. As such, the active matrix type OLED display device can maintain an emission state during an image display period regardless of the number of gate lines. In accordance therewith, the active matrix type OLED display device can provide sufficient brightness using little current. Therefore, the active matrix type OLED device can realize low power consumption and a large size.
Red, green, blue and white sub-pixels of an OLED display device according to the related art each include an OLED display element and a driving transistor. The driving transistor is used to adjust a current flowing through the OLED display element.
A current flowing through the driving transistor can be adjusted by a potential difference between gate and source electrodes of the driving transistor. The current flowing through the driving transistor is applied to the OLED display element. As such, the OLED display element can emit light. In other words, the quantity of light emitted from the OLED display element can be controlled by adjusting a voltage which is applied to the driving transistor. However, it is difficult for the related art OLED display device to obtain optimized brightness due to a threshold voltage deviation between the driving transistors.